共查询到19条相似文献,搜索用时 52 毫秒
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用量子主方程理论研究了量子点-腔耦合系统。为了说明理论模型,分析了一个量子点微柱腔强耦合(SC)实验。经研究发现耦合系统在稳态时抽运产生一个新的强耦合标准,抽运可以抑制或者增强强耦合;腔发射谱双峰结构并不是强耦合的明确特征,它还依赖于非相干抽运。研究表明,强耦合经常出现变相的单峰而弱耦合(WC)出现双峰结构与系统所控制的参数值密切相关。激子抽运增加时,腔发射谱由双峰逐渐变成增宽的单峰最后变成窄的单峰;腔衰减率增加时,均为双峰结构的腔发射光谱经历了从强耦合到弱耦合的转变。量子点腔失谐系统有效耦合强度与非相干抽运密切相关。 相似文献
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在GaAs衬底上用分子束外延分别生长了单层和五层垂直堆垛的InAs/GaAs量子点结构.室温光致发光实验表明,五层堆垛结构较单层结构的发光峰位红移180nm,实现了1.3μm发光.结合透射电镜分析,多层堆垛量子点材料发光的显著红移是由于量子点层间应力耦合导致的上层量子点体积增大以及各量子点层间的能态耦合. 相似文献
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两量子点耦合时,根据简并态微扰理论,单量子点的一个能级分裂为系统的两个能级,即对称态和反对称态,当单电子从外部隧穿进入一个量子点时,则电子在两耦合的量子点间振荡,本文讨论了电子在两能级上分布几率随时间的演化规律。 相似文献
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V. N. Nevedomskii N. A. Bert V. V. Chaldyshev V. V. Preobrazhenskii M. A. Putyato B. R. Semyagin 《Semiconductors》2009,43(12):1617-1621
Epitaxial GaAs layers containing InAs semiconductor quantum dots and As metal quantum dots are grown by molecular beam epitaxy.
The InAs quantum dots are formed by the Stranskii-Krastanow mechanism, whereas the As quantum dots are self-assembled in the
GaAs layer grown at low temperature with a large As excess. The microstructure of the samples is studied by transmission electron
microscopy. It is established that the As metal quantum dots formed in the immediate vicinity of the InAs semiconductor quantum
dots are larger in size than the As quantum dots formed far from the InAs quantum dots. This is apparently due to the effect
of strain fields of the InAs quantum dots upon the self-assembling of As quantum dots. Another phenomenon apparently associated
with local strains around the InAs quantum dots is the formation of V-like defects (stacking faults) during the overgrowth of the InAs quantum dots with the GaAs layer by low-temperature molecular
beam epitaxy. Such defects have a profound effect on the self-assembling of As quantum dots. Specifically, on high-temperature
annealing needed for the formation of large-sized As quantum dots by Ostwald ripening, the V-like defects bring about the dissolution of the As quantum dots in the vicinity of the defects. In this case, excess arsenic
most probably diffuses towards the open surface of the sample via the channels of accelerated diffusion in the planes of stacking
faults. 相似文献
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渐逝波耦合半导体量子点光纤放大器 总被引:1,自引:0,他引:1
基于半导体量子点的特性,结合光纤渐逝波耦合器,提出了一种新型的光纤放大器件,它将以溶液形式的硫化铅(PbS)半导体量子点材料沉积于耦合器熔锥区,信号光和抽运光通过渐逝波共同与半导体量子点材料相互作用,实现光的放大作用。PbS量子点材料是采用工艺容易控制的反胶束法制备的,通过透射电镜(TEM)测量得到其粒子尺寸小于10 nm。利用工作波长为980 nm,功率为30 mW的半导体激光器抽运光源对该光纤放大器抽运,在1310 nm波段得到了大于4 dB的增益,这是半导体量子点尺寸效应引起的光谱蓝移现象的体现。因此,这种有源区短、器件结构紧凑的光纤放大器在高速、宽带光纤接入等领域具有重要的实际意义和应用价值。 相似文献
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Irene DAmico 《Microelectronics Journal》2006,37(12):1440-1441
We propose a quantum bus based on semiconductor self-assembled quantum dots. This allows for transmission of qubits between the different quantum registers, and could be integrated in most of the present proposal for semiconductor quantum dot-based quantum computation. 相似文献
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Akiyama T. Sugawara M. Arakawa Y. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2007,95(9):1757-1766
This paper reviews the recent progress of quantum-dot semiconductor optical amplifiers developed as ultrawideband polarization-insensitive high-power amplifiers, high-speed signal regenerators, and wideband wavelength converters. A semiconductor optical amplifier having a gain of > 25 dB, noise figure of < 5 dB, and 3-dB saturation output power of > 20 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm, the record highest among all the semiconductor optical amplifiers, was realized by using quantum dots. By utilizing isotropically shaped quantum dots, the TM gain, which is absent in the standard Stranski-Krastanow QDs, has been drastically enhanced, and nearly polarization-insensitive SOAs have been realized for the first time. With an ultrafast gain response unique to quantum dots, an optical regenerator having receiver-sensitivity improving capability of 4 dB at a BER of 10-9 and operating speed of > 40 Gb/s has been successfully realized with an SOA chip. This performance achieved together with simplicity of structure suggests a potential for low-cost realization of regenerative transmission systems. 相似文献
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A. A. Tonkikh G. E. Tsyrlin V. G. Talalaev B. V. Novikov V. A. Egorov N. K. Polyakov Yu. B. Samsonenko V. M. Ustinov N. D. Zakharov P. Werner 《Semiconductors》2003,37(12):1406-1410
Heterostructures with In(Ga)As/GaAs quantum dots and quantum wells grown at low substrate temperature were studied by reflection
high-energy electron diffraction, transmission electron microscopy, and photoluminescence methods. It is shown that InAs deposited
onto (100) GaAs surface at low substrate temperature forms 2D clusters composed of separate quantum dots. Optical spectra
of structures containing such clusters demonstrate emission in the 1.5–1.6 μm range.
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Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 12, 2003, pp. 1456–1460.
Original Russian Text Copyright ? 2003 by Tonkikh, Tsyrlin, Talalaev, Novikov, Egorov, Polyakov, Samsonenko, Ustinov, Zakharov,
Werner. 相似文献
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A. E. Zhukov A. R. Kovsh V. M. Ustinov A. Yu. Egorov N. N. Ledentsov A. F. Tsatsul’nikov M. V. Maksimov S. V. Zaitsev Yu. M. Shernyakov A. V. Lunev P. S. Kop’ev Zh. I. Alferov D. Bimberg 《Semiconductors》1999,33(9):1013-1015
The current dependence of the optical gain in lasers based on self-organized InGaAs quantum dots in a AlGaAs/GaAs matrix is
investigated experimentally. A transition from lasing via the ground state of quantum dots to lasing via an excited state
is observed. The saturated gain in the latter case is approximately four times greater than for the ground state. This result
is attributable to the fourfold degeneracy of the excited level of quantum dots. The effect of the density of the quantum-dot
array on the threshold characteristics is investigated. A lower-density array of dots is characterized by a lower threshold
current density in the low-loss regime, because the transmission current is lower, while dense quantum-dot arrays characterized
by a high saturated gain are preferable at high threshold gains.
Fiz. Tekh. Poluprovodn. 33, 1111–1114 (September 1999) 相似文献
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采用飞秒激光流动烧蚀法制备了聚乙烯亚胺(PEI)包覆的ZnSe量子点水相分散液。水相分散液外观呈现亮黄色透明液体状。多个ZnSe有机复合量子点在水中聚集形成球形胶束,通过扫描电子显微镜(SEM)检测发现,胶束粒径为40~100 nm。利用高分辨透射电子显微镜(HRTEM)和X射线衍射(XRD)研究ZnSe晶体学特性变化,结果表明制得的ZnSe量子点保持了块体ZnSe的立方闪锌矿晶型。该ZnSe有机复合量子点的水分散液在365 nm紫外光照射下显示出明亮的绿色荧光,荧光中心波长约在500 nm处。采用光致发光光谱和紫外可见吸收光谱研究了该有机复合量子点的pH值响应特性,结果表明随着分散液中pH值由9降低到4,光致发光光谱显示出蓝移特性,波长最大蓝移量为25 nm。讨论了绿色荧光的来源与荧光波长调谐的可能机理。 相似文献